Intro Flashcards
deals with the characterization of the individual sediments
Sedimentolgy
Broad scientific discipline that encompasses the study of all kinds of sedimentary rocks
SedPet
Fundamental Constituents
Terrigenous
Chemical/Biochemical
Carbonaceous
Authigenic
- These sediments are derived from terrestrial environment
- From any rock type, including older sedimentary rocks
- Minerals and rock frags transpo to depositional basins (extrabasinal origin)
- Grains make up STS, CGL, SHL
Terrigenous Constituents
in terrigenous constituents, ___ are often found as a result of recombination and crystallization from parent rocks during
weathering
Fe-Oxides and clay minerals
- generated at weathering sites by recombination and crystallization
Secondary Minerals
- Derived from the precipitates
- Soluble constituents e.g. calcite, gypsum
- Examples are ooids and pellets
- Includes limestones, cherts, evaporites,
phosphorites
Chemical/Biochemical
chemical/biochem processes are seen within______
Depositional Basins
- lead to extraction from basin water of soluble constituents
- forms minerals such as Cal, Gy, Ap
- forms calcareous and siliceous shells of organisms
- precipitations aggregated into silt or sand-size grains
- moved about by current and waves within depositional basins
- ex. Carbonate ooids and pellets
- makes up Intrabasinal seds
- ex. LST, Chert, Evaporites Phosphorites
Chemical/Biochemical Constituents
Composed of carbonized residues of terrestrial plants, animals and petroleum bitumen
Carbonaceous
- woody plant tissue residue
-most constituents of coal
Humic
Spores, pollen, phyto- and zooplanktons, and macerated plant debris in water; constituents of cannel coals and oil shales
Sapropelic
solid, asphaltic residue form from petroleum through the loss of volatiles, oxidation and polymerization
Bitumens
-Minerals precipitated from pore waters within the sedimentary pile during burial diagenesis
- may include Silicate and Non silicate minerals
- can be added during burial but are never the dominant constituents of seds
Authigenic (Secondary) Constituents
Sed rocks cover about ? of the surface
80%
Average thickness of Earth’s sedimentary shell is ?km
2.2
the volume of sedimentary rocks of Earth’s crust is concentrated on the continents (?%surface)
29
About ? percent of sedimentary rocks occur on the continental shelf and continental slope (?% surface)
13;14
Approximately ? percent of the total volume of sedimentary rocks occurs on the floors of the oceans (?% surface)
17;58
rocks that make up Earth’s sedimentary shell are mainly shales ?, sandstones ?, and carbonate rocks ?%
50;24;24
T or F
relative volume of preserved shale per unit age has not changed significantly since early/ middle (Archean) Precambrian time.
T
Number of recycling times a seds has undergone is a *function of
tectonic setting and the susceptibility of rocks to be weathered+eroded*
Tectonic Setting (climate) governs
weathering/erosion intensity
Rock type determined relative ease of destruction. Ranking
- Evaporites
- Limestones
- Dolomites
- Shales, Sandstones, Volcanogenic sediments
Evaporite rocks are recycles upto ? times in the GTS
15
carbonate rocks are recycles upto ? times in the GTS
10
SHL and STS are recycles upto ? times in the GTS
5
Two possible models for sediment recycling
Constant Mass Model and
Linear Accumulation Model
- Early degassing
- All water along with acidic gasses that can react with early igneous rock has been released
- Since then, there haven’t been any such degassing events which means no gasses, which meant that no completely new sediment has been created
- Through time, seds have been recycled by erosion/destruction via metamorphism and recycling of CO2 and HC
Constant Mass Model
- water, CO2 and HCl are continuously degassed from earth at a linear rate
-
New sedimentary rocks have thus continued to form through time by the breakdown of primary igneous rock.
-the mass of sediments has grown linearly through time from zero to the currently existing mass.-
Linear Accumulation Model
Sedimentary basins are now commonly classified in terms of
- (1) the type of crust on which the basins rest,
- (2) the position of the basins with respect to plate margins, and
- (3) for basins lying close to a plate margin, the type of plate interactions occurring during sedimentation
The rate of basin subsidence, together with rates of sea-level rise or fall, determines the ???? – the space available at any time in which sediments can accumulate.
Accumulation Space
The size and shape of the basins, which places ????? that can accumulate.
limits on the volume of sediments
- Terrestrial Rift Valleys
- commonly associated with bimodal volcanism;
- ex. Rio Grande Rift, NM
Divergent Settings
- Incipient oceanic crust and flanked by young rifted
- continental margins; ex. Red Sea
- Proto-Oceanic Rift Troughs
- Mature rifted continental Margins in intraplate settings at continental oceanic interfaces
- Continental Rise and Terraces
- Progradational sediment wedges formed of rifted continental margins
- Continental embankments
Broad cratonic basins floored by fossil rifts in axial zones
- Intracratonic Basins
- Stable cratons covered with thin laterally extensive sediment cover
- Continental Platforms
Basins floored by oceanic crust formed at divergent plate boundaries unrelated to arc-trench systems (spreading still active).
Active ocean basins
- Former failed rifts at high angles, which have been reactivated during convergent tectonics
Aulacogens
rifts formed at high angles to continental margins, without preorogenic history
Impactogens
Basins formed in intermontane settings following the cessation of local orogenic or taphrogenic activity
Successor Basin
Sedimentary aprons and platforms formed in intraoceanic settings other than magmatic arcs.
Oceanic islands, aseismic ridges
and plateaus:
Basins floored by oceanic crust, which is neither spreading nor subducting (no active plate boundaries within or adjoining basin).
Dormant ocean basins:
Deep troughs formed by subduction of oceanic lithosphere.
Modern example: Chile Trench
Trenches:
Local structural depressions developed on subduction complexes.
Modern example: Central America Trench
Trench-slope basins:
Basins within arc-trench gaps. Modern example: Sumatra
Forearc basins:
Basins along arc platform, which includes superposed and overlapping volcanoes. Modern example: Lago de Nicaragua
Intraarc basins
Oceanic basins behind intraoceanic magmatic arcs (including interarc basins between active and remnant arcs), and
continental basins behind continental- margin magmatic arcs
Backarc basins:
Foreland basins on continental sides of
continental-margin arc-trench systems (formed by subduction-generated compression and/or collision). Modern
example: Andes foothills
Retroarc foreland basins:
Shrinking ocean basins caught between colliding continental margins and/or arc-trench systems, and ultimately subducted or deformed within suture belts. Modern example: Bay of Bengal
Remnant ocean basins:
Foreland basins above rifted continental margins that have been pulled into subduction zones during crustal collisions (primary type of collision-related forelands). Modern example: Persian Gulf
Peripheral foreland basins:
Basins formed and carried atop moving thrust sheets. Modern example: Peshawar Basin (Pakistan)
Piggyback basins:
Basins formed among basement-cored uplifts in foreland settings. Modern example: Sierras Pampeanas basins (Argentina)
Foreland intermontane basins
(broken forelands):
Basins formed by extension along strike-slip fault systems.
Modern example: Salton Sea (California)
Transtensional basins:
Basins formed by compression along strike-slip fault systems.
Modern example: Santa Barbara Basin (California)
(foreland)
Transpressional basins:
Basins formed by rotation of crustal blocks about vertical axes
within strike-slip fault systems. Modern example: Western
Aleutian forearc
Transrotational basins:
Diverse basins formed within and on continental crust due to
distant collisional processes. Modern example: Qaidam
Basin (China)
Intracontinental wrench basins
Former failed rifts at high angles to continental margins, which
have been reactivated during convergent tectonics, so that they
are at high angles to orogenic belts. Modern example:
Mississippi embayment
Aulacogens:
Rifts formed at high angles to orogenic belts, without preorogenic
history (in contrast with aulacogens). Modern example:
Baikal rift (Siberia) (distal)
Impactogens:
Basins formed in intermontane settings following cessation of
local orogenic or taphrogenic activity. Modern example:
Southern Basin and Range (Arizona)
Successor basins:
